Physicochemical analysis of aS1-, b- and k-casein solubility in 45% ethanol

The casein fractions solubility in 45% ethanol at T = 293 K as a function of pH and the electrostatic surface energy (V-E) can be represented by an equation describing the ionisation process. The half solubility of alpha(S1)-, beta- and kappa-caseins is observed respectively at pH: 6.54, 6.85 and 6.85 at V-E: 38, 19 and 0.3 k(B).T. The solubility increases from 10% to 90% for the change in pH by 0.78, 0.84 and 1.08, and in V-E by 22, 11 and 0.6 k(B).T, respectively. For the solubility presented as a function of the reduced V-E, the behaviour of kappa-casein is different from alpha(S1)-, beta-caseins. The fraction of an industrial sodium caseinate, soluble in 45% ethanol at pH 6.4 and 293K is enriched to about 60% in alpha(S1)-casein. This fraction could be used as an emulsifying agent or for cream liqueur production